The WTC Advisory note was "in force" from 2001-2005, and so could be used in the future to "test" the work of actuaries in that period. It was superseded by the Large Loss Advisory Note in 2005.
All the information contained in the data library has been located in publicly available sources. Whilst every endeavour has been made to keep the information as up to date as possible, it is possible that some information is either out of date or has now been revised.